The Groove-Necked Bottle: Three Threads in the Neck That Hold the Cork

"Lastly, between sections A and C is placed section B, constituted of three parallel grooves or worms extending from section C to section A in the form of the screw. These grooves are one-eighth of an inch in depth and wind once around this section of the tool, and each groove or wire is beveled from the lower part of itself to the outer part of the next above parallel groove. All the grooves are cut or shaped a little dove-tailing, so that when the neck of the bottle or other vase is molded or formed to the tool or pattern there will be in the neck of the complete bottle an edge which will hold the cork to its place." "The cork, having been compressed, easily descends the neck of the bottle, meeting from this formation of the neck of the bottle with no obstruction in its downward progress; but once there, it expands from its own elasticity, so as readily to fill these grooves, and the wire of the grooves, formed as above, there confines it securely; nor can it escape, however great the upward pressure applied below, until external aid is furnished by unscrewing it."

**Neck.** Model a block 35 × 35 × 45 mm with a bore through it shaped like Kendall's core: 14 mm across at the bottom (his 9/16 inch), widening at a shoulder to 21 mm (13/16 inch), and above the shoulder three parallel grooves 3 mm deep (1/8 inch) that wind once round in 25 mm, each bevelled so that it narrows upward and has a square edge facing up. Print it in PLA, with the bore upright. **Cap.** Drill a 12 mm hole in a carbonated-drink bottle cap and epoxy it under the block, holes lined up. **Bottle.** Fit a snap-in tyre valve through the base of the bottle so it can be pumped. **Test.** Squeeze a cork a little wider than the grooved bore with pliers, push it down the neck past the grooves, and let it swell for an hour. Wearing safety glasses and pointing the neck away, pump the bottle in steps of 0.5 bar up to 2 bar, reading the pump's gauge, and watch the cork. Let the air out, then take the cork out by twisting it with a corkscrew and note which way it has to turn.

**Thomas Kendall** of San Francisco, California, received US 11,895, dated 7 November 1854. His core, tap or tool could be of clay, stone or mineral; section A at its base was 9/16 inch across, the shoulder 13/16 inch, and a flange C above the grooves carried a tenon for a handle. His claim is the bottle, jug or jar with a tri-threaded screw in the neck of the bevelled form given by the core. **Honest limits.** A printed PLA neck on a plastic bottle's cap stands in for a neck moulded to his core, and pumped air for the gas of the drink. The notebook treats the grooves as a plain screw; its diameters and friction coefficients are examples. Your cork under pressure is the result.